Peer Empowerment Program for Physical Activity in Low Income & Minority Seniors Older adults are the least active population group in the US. Yet, research has shown that an increase in physical activity (PA) can have immediate and profound effects on cardiovascular health. Older adults who are active use significantly fewer health care resources, and with the increasing number of older adults in the US it is imperative to curb health care expenditure in this group. Many PA interventions are flawed because they focus on individual motivations and ignore variations in community resources, neighborhood walkability, and safety. Low income and ethnically diverse communities have disproportionately fewer resources and less supportive neighborhoods. This contributes to lower PA levels and health disparities in obesity, diabetes, hypertension and heart disease. National and international health institutions have called for community based PA programs to improve population health. Senior centers are an ideal setting for PA interventions because they serve a large number of older adults and there are funding mechanisms for delivery of evidence based programs. While there are multiple benefits of different PA programs, national guidelines for PA still emphasize aerobic activity. Senior Centers currently offer group based PA programs but our preliminary studies show that 1) low income, ethnically diverse older adults attending such centers are not meeting PA guidelines, 2) evidence based programs in such centers do not generate moderate intensity PA, 3) they do not provide behavioral strategies to support more frequent and independent PA and 4) members are not involved in the delivery of such programs which may increase engagement and sustainability. We propose to build upon our NHLBI R01 funded PA program that increased aerobic activity in retirement community residents. The program was delivered by UCSD health educators for 6 months with the help of peer leaders who then sustained it over 12 months. To improve upon this work, we propose a train the trainer model with a greater focus on empowering the peer leaders, center staff and participants to self-monitor, self-organize and advocate for additional resources from the start. Since our aim is to test a PA program that can be adopted by local area aging agencies with Older Americans Act Title IIID funds, we will employ an effectiveness-implementation hybrid design; which allows for the concurrent testing of both intervention and implementation strategies and outcomes. We will also extend program monitoring to 24 months. Thus, in a 2-year cluster randomized controlled field trial of 408 ethnically diverse, older adults (50+ years old) in 12 low income Senior Centers in San Diego County we will investigate the efficacy of PEP4PA (Peer Empowerment Program 4 Physical Activity) to reduce disparities in PA by increasing the percentage of participants achieving 150 minutes of PA per week and to improve physical functioning & fitness, blood pressure, depressive symptoms and quality of life at 6, 12 & 24 months. We will assess the incremental cost effectiveness ratio of PEP4PA in terms of cost per MET hour and cost per QALY compared to usual programming in the control centers at 12 & 24 months.